Is it OK to completely close a valve?

georgearoush

In a one-pipe steam radiator system, is it OK to completely close the valve if I want to prevent a room from heating up?

Jamie Hall

That's actually a rather hard question to answer. Theoretically, of course, the answer is yes. However, that answer comes with a caution: the valve must, in fact, close completely. A new valve is likely to do that. An older valve — particularly one which has been in use in steam service for quite some time — is very likely to not do that.

Why is this an issue? Because a valve which does not truly close completely will allow some steam into the radiator — a small amount, most likely, but some — and that will condense in the radiator. The trouble is — that condensate may very well not be able to get out the way it got in. Valves tend to be tighter against liquids than they are against gases. Not that the radiator will fill completely — but enough condensate may accumulate to cause some noise problems.

On the whole it is probably better to keep a one pipe radiator from heating — much — by closing its vent. That won't turn it off completely, but it will keep it from developing all that much heat.

delcrossv

Simply spinning the vent upside down will close it.